二步阳极氧化法制备TiO_(2)纳米管阵列复合MoS_(2)的光电化学性能研究

Photoelectrochemical Properties of TiO_(2) Nanotube Array Composite MoS_(2) Prepared by 2-step Anodization Method

目的 探索二步阳极氧化工艺对TiO_(2)纳米管复合MoS_(2)后样品的光电化学及半导体性能的影响。方法 利用直流脉冲稳压电源对TA1进行阳极氧化工艺处理,电压为40 V,使用的电解液为乙二醇+氯化铵水溶液,再采用220℃、6 h水热法在TiO_(2)纳米管上生长MoS_(2),得到TiO_(2)/MoS_(2)的异质结构。使用扫描电镜(SEM)观察样品的表面微观形貌,利用X射线衍射仪(XRD)分析二步阳极氧化复合MoS_(2)的晶体结构,采用光致发光光谱仪(PL)对样品光生电荷重组进行分析,使用EDS分析复合前后的成分变化,通过电化学工作站对制备的各类样品进行光电流密度、电化学阻抗和莫特肖特基曲线分析。结果 在50 min时一步阳极氧化TiO_(2)纳米管具备良好的电化学及半导体性能,再经过二步阳极氧化工艺制备了2-step TNTs样品,在此基础上复合MoS_(2),可以显著提高其电流密度,提升了大约60%,达到0.32m A/cm^(2),通过等效电路拟合得出此时的Rct为298?,光致发光强度明显减弱。结论 TiO_(2)纳米阵列能为MoS_(2)提供丰富的生长位点,也提供了许多载流子转移通道,通过协同作用来提升光电化学性能。通过二步阳极氧化法制备TiO_(2)纳米管阵列复合MoS_(2)的样品其电荷转移电阻明显降低,形成更便捷的电子传输通道,载流子的迁移速率变得更快,具有较高的电子-空穴分离效率。这一研究为二步阳极氧化复合膜的制备与性能改善提供了一种新的思路。

The surface modification of titanium sheet(TA1)can effectively improve its comprehensive performance.The common surface modification technologies of titanium alloy are electroplating,electroless plating,anodic oxidation,micro-arc oxidation,etc.The titanium oxide material prepared by electrochemical anodic oxidation has good photocatalytic activity,high chemical stability,low cost and non-toxicity.Titanium dioxide has a special structure and good performance,and has long been attention as an excellent photoelectric catalyst.In order to explore the effect of 2-step anodization process on the photoelectrochemical and semiconductor properties of TiO_(2) nanotubes composited with MoS_(2),in this experiment,the titanium sheet(TA1)was used as the matrix,and the size of the pattern was cut into 30 mm×10 mm×1 mm.The cut sample was pre-treated,and the surface of TA1 was polished with different types of sandpaper in turn so that there was no obvious scratch on the surface.Then it was washed with deionized water,ultrasonically cleaned and dried.The titanium sheet was anodized by a DC pulse stabilized power supply.The voltage was 40 V,and the electrolyte used was ethylene glycol+ammonium chloride aqueous solution.The sample after two-step anodization was placed in a high-pressure reactor containing thiourea and sodium molybdate.MoS_(2) was grown on TiO_(2) nanotubes by hydrothermal method at 220℃for 6 hours to obtain a 2-step TiO_(2)/MoS_(2) heterostructure.The surface morphology of the sample was observed by scanning electron microscopy(SEM).The composite MoS_(2) nanoparticles were uniformly grown on the tube wall of the nanotube.The crystal structure of the two-step anodization composite MoS_(2) was analyzed by X-ray diffractometer(XRD).The characteristic peaks of MoS_(2) were also observed,and no other characteristic peaks appeared.The photogenerated charge recombination of the samples was analyzed by photoluminescence spectrometer(PL).The photoluminescence intensity of 2-step TNTs 50 min/MoS_(2) was much weaker than that of other samples.EDS was used to analyze the composition changes before and after compounding.The photocurrent density,electrochemical impedance and Mott-Schottky curve of the prepared sample were analyzed by an electrochemical workstation.The performance of the two-step anodized TiO_(2) nanotube composite MoS_(2) was greatly improved.The 2-step anodized TiO_(2) nanotubes have good electrochemical and semiconductor properties at 50 min.On this basis,the composite MoS_(2) can significantly increase its current density by about 60%,reaching 0.32 mA/cm^(2).The equivalent circuit fitting shows that the Rct at this time is 298Ω,and the photoluminescence intensity is obviously weakened.TiO_(2) nanoarrays can provide abundant growth sites for MoS_(2),and also provide many carrier transfer channels for improving the photoelectrochemical performance through synergy.The charge transfer resistance of the TiO_(2) nanotube array composite MoS_(2) sample prepared by the two-step anodization method is significantly reduced,forming a more convenient electron transport channel,the carrier migration rate becomes faster,and the electron-hole separation efficiency is higher.This study provides a new idea for the preparation and performance improvement of the 2-step anodization composite film.